Method to render cellulose resistant to creasing and wrinkling and the product thereof



Richard L. Doerr, Niagara Falls, N.Y., and Robert L.

Holbrook, Riderwood, Md, assignors to 01in Mathieson Chemical Corporation, a corporation of Virginia N Drawing. Application December 9, 1958 Serial No. 779,058

19 Claims. (Cl. 8116.3)

This invention relates to the treatment of cellulosic textiles to impart wrinkle resistance thereto. More particularly it relates to the impregnation of textiles with solutions containing formaldehyde and a hydrazide.

The use of hydrazide-formaldehyde reaction product to impart wrinkle resistance to textiles has been briefly described in U.S. 2,161,808. The latter generally implies that resistance to creasing and crushing of textiles can be improved by impregnating them with reaction products of hydroxylamine or hydrazine or derivatives of these bodies with formaldehyde or other aldehydes or substances yielding or acting as aldehydes. The process involves dipping the textile in an aqueous solution of the hydroxylamine or hydrazide derivative, drying the textile, impregnating it with an aldehyde and finally curing the textile by heating. It has been experimentally determined that while the treatment of textiles as described in US. 2,161,808 does impart some crease resistance to cellulosic textiles, however, the product has several disadvantages which render it non-competitive with those produced by current processes. The most serious drawbacks are an inferior crease resistance and a large loss in the tensile strength of the textile.

The use of polymethylol hydrazides of dibasic acids as antiwrinkling or creaseproofing agents is described in pending applications Serial Numbers 731,146 and 731,- 147, filed April 28, 1958 of R. L. Holbrook and R. L. Doerr. These applications describe the preparation of the polymethylol hydrazides of dibasic acids, by reaction of formaldehyde and dihydrazides of dibasic acids, and their application to cellulosic textiles. The finishes produced are superior to any in general commercial use with respect to durable wrinkle resistance and absence of chlorine retention upon bleachingtwo of the most important properties of an antiwrinkling agent. Although these polymethylol hydrazides of dibasic acids are generally superior to prior antiwrinkling agents they suffer two disadvantages which require special attention. The first of these involves their aqueous solutions which are not stable. The padding bath, i.e., the dilute aqueous solution into which the textile is immersed in order to impregnate it with the dissolved antiwrinkling agent, has a tendency to form insoluble resins due to polymerization. For this reason, the bath cannot be stored for any appreciable time, but must be prepared daily by admixing Weighed amounts of the hydrazide and the formaldehyde in water at a controlled temperature and pH as described in the above mentioned applications of Holbrook and Doerr. The second and more serious drawback of cellulosic textiles treated with polymethylol hydrazides of dibasic acids is their tendency to remove copper from aqueous solutions. The textiles become slightly discolored at first, the discoloration accumulates during subsequent exposures until the cloth becomes light green. As little as 0.2 parts per million by weight of copper ions in aqueous solution is sufiicient to produce a visible discoloration of white cloth in one exposure, e.g., a wash or rinse. This problem exists wherever the water supply 2,904,390 Patented Sept. 15, 1959 contains sufficient copper or when the water resides in copper plumbing for a substantial period prior to its use. Under certain conditions of pH and carbon dioxide content, water can dissolve up to 0.5 parts per million by weight of copper by being in a copper pipe for only several hours. The discoloration cannot be completely removed from the treated cloth except by severe treatments which generally weaken the fibers, thus reducing the tensile strength of the cloth.

It has now been found that polymethylol hydrazides of monocarboxylic acids can be made to impart a high degree of wrinkle resistance to cellulosic textiles without the disadvantages associated with the use of polymethylol hydrazides of dibasic acids or those inherent in the process "described by U.S. Patent 2,161,808. This invention provides a process for treating cellulosic textiles to improve their antiwrinkling properties and to produce a finish which can be bleached as often as desired without fear of chlorine retention and resultant discoloration and fiber damage. The finish does not pick up copper from water containing traces thereof with resultant discoloration. Furthermore the finish is durable and yet the treatment is not seriously detrimental to either the tensile strength of the cloth orits hand, or feel. When prepared as described below many of the polymethylol hydrazides of monobasic acidsare stable in aqueous solution. Thus the padding can'be accomplished by a single dip in one bath which will not form resinous products throughout its useful life. When prepared and applied as described below the polymethylol hydrazides of monobasic acids are superior antiwrinkling agents and their use is inexpensive since these compounds are prepared from readily available starting materials and applied with existing padding equipment.

According to this invention the padding bath is prepared by first reacting formaldehyde (or convenient sources thereof such as paraformaldehyde) with a hydrazide having the formula RCONHNHR wherein R is H or an alkyl or substituted alkyl group and R is H or o Rt- The R of the formula and the R ofthe R group can be the same or different. Preferably, the al-kyl group contains from 1 to 8 carbon atoms and the substituted alkyl group is substituted by hydroxyl or sulfhydryl groups. Examples of preferred hydrazides include diformic hydrazide, acetic hydrazide, diacetic hydrazide, glycolic hydrazide, thioglycolic hydrazide, propionichydrazide, and gluconic hydrazide. The order of addition is not critical. It is preferable, however, to add an aqueous solution of the hydrazide slowly to aqueous formaldehyde while maintaining the pH of the mixture at about 7 to 10, preferably 7 to 9, by the incremental addition of a dilute base, e.g., aqueous sodium hydroxide. In this way the formation of any resinous products is prevented. The reaction is preferably carried out at a temperature from about 10 about 50 C. although lower and higher temperatures can be used. Although it is preferable to use a readily water-soluble hydrazide, it is not absolutely-necessary since the polymethylol re action product is generally sufiiciently soluble to pre' pare the padding solution. The polymethylol hydrazides of slightly soluble hydrazides can be prepared by reacting aqueous formaldehyde with an aqueous suspension of the hydrazide. The mole ratio of formaldehyde to bydrazide should bebetween 2 and 20 (preferably 4 and 8), to 1. It has been established that less than 2 and more than about 20 moles of formaldehyde per mole of hydrazide causes inferior crease angles and excessive loss in tensile strength by the textile. After dissolution of the hydrazide is complete the solution should contain about 80 percent to about 95 percent by weight water, the remainder being the formaldehyde and the hydrazide in the mole ratio recited above. The solution is then allowed to stand for about one-half to 6 hours during which time the pH generally drifts to between about 4 and 6. Although the latter step is not essential to the preparation of an operative bath it is necessary if the maximum anti-wrinkling properties are desired. After the addition of 0.1 percent to 2.0 percent by weight based on the weight of the solution of a suitable catalyst the bath is ready to be applied to cellulosic textiles. The addition of the catalyst makes the crease/proofing more durable, i.e., resistant to laundering. There is no general formula for suitable catalysts. Among those found suitable are magnesium chloride, ammonium p-toluene sulfonate, iso-propanol amine hydrochloride. Minor proportions of additives such as wetting agents, softeners, etc. can also be added to the bath.

In accordance with the invention a solution prepared as described above and containing from about 5 percent to about 20 percent or more by weight of the reaction product of 2 to 20 or more moles of formaldehyde with one mole of the hydrazide or mixture of hydrazides is padded onto the cloth, in the usual manner and preferably while the padding bath has a pH from about 5 to about 7, to the extent that the dry pick-up or add-on, after the cloth is cured, is between about 2 percent and 15 percent by weight, based on the weight of the dry cloth. This add-on is generally accomplished by a wet pick-up of about 65 to 85 percent with the baths de scribed above. An add-on or dry pick-up of over 15 percent can be used but there is generally insufiicient added advantage to justify this.

The curing step, i.e., the reaction of the formaldehydehydrazide adduct with the textile is carried out by standard procedure. Thus, the wet textile is subjected to an elevated temperature until dry and then further heated in the table below indicates the percent by weight of formaldehyde and hydrazide in the solution based on the weight of the solution. The percent by weight of catalyst shown is also based on the weight of the solution. The percent 'wet pick-up is based on the increase in weight of the cloth due to its solution content. The cure time and temperature indicates the duration of time the cloth was heated at the temperature indicated after being dried on a dry can at about 90 C. for several minutes. After the curing step the cloths were scoured, i.e., agitated in a bath at 60 C., containing a wetting agent and a percarbonate or a perborate. They were then rinsed free of suds, dipped into a 1 percent by weight acetic acid solution for 15 seconds at about C., and finally rinsed in water. After being pressed with an iron until almost dry the test pieces of cloth were placed in a constant humidity percent RH.) and temperature (72 F.) room for 24 hours in order to standardize the cloth for testing. The crease angle of the cloths were determined by folding a small section of each cloth in half under pressure, releasing the pressure and measuring the angle to which the cloth opened (AATCC Tentative Test Method 66-53). The tensile strength was determined by means of a Scott Tensile Tester which subjects the cloth to a measured stretching force until it pulls apart. The tensile strength is recorded as the number of pounds required to pull apart a strip of cloth one inch wide. The cloth was 78 x 84 white cotton sheeting having an original crease angle of 71 and a tensile strength of pounds.

Thus, the process of this invention gives rise to textiles having superior crease resistance. Furthermore, when cloths treated in this manner were bleached, e.g., in dilute aqueous hypochlorite simulating home laundering conditions, it was found that none of them retained chlorine, or showed any adverse efiects from being in its presence.

hydrazide (grams) water (grams) 27% OHZO (grams) Use Level (percent)... mole ratio of CHzO/hydrazide. catalyst (percent) Approx. wet pick-up (percent) glycolic, 3. diformic, 8.8... l 21 21 i diacetie, 11.6. 2

propionic, 4.4. 168

cure time (mins.) and temp. 0.). 4, 183 crease angle 130- tensile strength (pounds) 30....

50.0. 10. 12:1. IPAlI, 1.4.

1 Isopropanol amine hydrochloride.

to effect the curing. Complete cure can be obtained by heating at 150 to 200 C. for /2 to 10 minutes. The curing period is temperature dependent and can be varied over a wide range. Thus, complete curing can also be attained in 15 to 60 seconds at temperatures above 200 C. After the cloth has been cured, it can be finished according to standard textile mill procedure. An alkaline scour generally follows the crease-proofing process to remove any excess, unreacted creaseproofing agent and to improve the hand, or feel of the cloth. Normal finishing operations can include calendering, framing, blueing, compressive shrinking, etc.

The following examples further describe this invention. In the examples, the term mole signifies gram moles.

Examples 1 to 5 Several solutions were prepared under the conditions shown in the table. The indicated amount of hydrazide was dissolved in the indicated amount of water and this solution was slowly added to the 37 weight percent aqueous formaldehyde. In each case the pH of the mixture was maintained between 7.2 and 9.3 throughout the mixing period by the incremental addition of 10 percent aqueous sodium hydroxide. The Use Level heading Example 6 Two solutions were made up having the following The solutions were prepared by slowly adding the hydrazide to a solution containing the water and aqueous formaldehyde. The solution was stirred during the mixing and its pH was maintained at about 8 by the incremental addition of aqueous caustic. After the solutions were prepared, a portion of each of them was set aside to compare their stability and a portion of each was padded onto a separate piece of 78 x 84 cotton sheeting to determine their antiwrinkling properties and copper retention.

In the padding operation, there was first added about 0.9 percent by weight, based on the weight of the solution, of magnesium chloride to each of the solutions. The cotton was then impregnated with the solution by Crease Tensile angle, strength,

degrees pounds The treated cloths were then washed in an aqueous solution containing 0.2 percent by Weight of a commercial detergent and 1.0 part per million by weight of cupric ion for 5 minutes at 140 F. The copper pick-up was indicated by the loss in brightness of the cloth as measured by a reflectometer. The table indicates the brightness reading after successive washes in the solution:

No. of washes A B The typical dibasic acid hydrazide-formaldehyde antiwrinkling agent picked up enough copper in one wash to show a discoloration of the cloth visible to the unaided eye. After 5 washings the cloth containing it had a greenish-yellow color which could not be removed by washing in copper-free water.

The stability of the portions of the solutions set aside at room temperature was observed at various intervals. After 4 days the polymethylol diglycolic hydrazide solution contained an insoluble gel which rendered it useless for creaseproofing, while the sample taken from solution A was still clear and colorless after 23 weeks.

Example 7 In order to compare the process described in Patent 2,161,808 with that of this invention, an experiment was carried out with the following aqueous solutions. The numbers indicate parts by weight:

A Acetic hydrazide 1.0 H 0 26 B N2H4 H2504 1. 0 H 0 19 C CH O 1;O H O 1.7

D CH O 1.00 H O 1.65 MgCl 0.021

Thus solutions A and B are typical padding baths as described in US. Patent 2,161,808. Solution C is a 37 weight percent formaldehyde solution while solution D is a similar formaldehyde solution but containing 0.8% of a typical catalyst according to the process of this invention.

Two cuttings of white cotton cloth were padded, one of them with solution A and one of them with solution B, according to the general process of US. Patent 2,161,808. The wet pick-ups were about They were then dried and the one padded with solution A was padded next with solution D (formaldehyde plus catalyst) while the one padded with solution B was secondly padded with solution C (aqueous formaldehyde). After curing both cloths for 5 minutes at C., the crease angle and tensile strength was measured according to the method described in Example 1:

Thus the two bath method was unable to give a satisfactory crease angle with an organic monobasic acid hydrazide, even with a catalyst present for the curing step, when applied according to the method of the abovementioned patent. The cloth treated with the hydrazine sulfate showed a satisfactory crease angle, however the fibers were severely damaged as demonstrated by the low force (11 pounds) required to pull apart a strip one inch wide. It has been found that inorganic salts, especially under acidic conditions, are generally detrimental to fiber strength of cellulosic textiles. In addition, the cloth treated with the hydrazine salt was discolored by the treatment having a yellowish cast.

A second experiment was made wherein an acetic hydrazide-formaldehyde reaction product was padded onto a cellulosic textile under the conditions described in this invention except that the curing step was carried out at only 130 C. for 5 minutes. These conditions are insuflicient for curing, since the cloth showed no improvement in crease resistance, i.e., the hydrazide and formaldehyde had not reacted with the cellulose and were completely washed out during the scouring step, one of the steps used to prepare the cloth for testing (see Example 1).

Examples 8 to 10 The following solutions were prepared by slowly admixing the aqueous hydrazide with aqueous formaldehyde in such proportion so as to produce the compositions shown in the table. After the catalyst was added to the solutions in the percentage shown, based on the bath weight, they were padded onto several cuttings of the cloths listed. The percent Wet pick-up is shown in the table as is the use level, curing time and temperature. The crease angles and tensile strengths were determined as described above:

8 9 10 Linen 1 Linen Rayon hydrazide (grams) water (grams) GHzO (grams) crease n l acetic 7.4 diacetic 1.2..- l colic 9.0. 230 sii.

1 This cutting was mercerized, prior to padding, by immersing undertension in 30% aqueous caustic for 15 minutes. It was then rinsed with water, in 5% acetic acid, again in water and dried.

2 This cutting was mercerized after being creaseproofed.

. Ammonium p-toluene sultonate.

The original properties of these cloths were:

Linen 1 Linen 1 Rayon Crease angle, degrees tensile strength, pounds 11? See footnotes in above table.

Example 11 methanol was placed therein. To the formaldehyde solution was slowly added 74. grams of acetic hydrazide. Finally, about 14 grams of water and 61 grams of methanol were added to complete the composition. The final composition contained 40% by weight of solids and 15% by weight of methanol and its pH after thorough mixing was 3.95. A portion of this solution was diluted with water until it contained 11% by weight of solids. About 0.8 percent of magnesium chloride, based on the weight of the solution was added to the solution and it was padded onto white cotton cloth, at a pH of 4.5. The wet pick-up was about 80 percent and the dry-add-on after drying and then curing the cloth at 360 F. for 3 minutes was about 8 percent. After the curing step the cloths were scoured at 60 C. in an aqueous perborate solution containing a wetting agent. They were rinsed free of suds, dipped into a 1 percent by weight acetic acid solution for 15 seconds at about 50 C. and finally rinsed in water. After being pressed with an iron until almost dry, the test pieces of cloth were placed in a constant humidity (60 percent RH.) and temperature (72 F.) room for 24 hours in order to standardize the cloth for testing. After the treatment the cloth had a crease angle of 129 and an average tensile strength of 34 pounds compared to original values of about 75 and 60 pounds.

Example 12 This example relates to the use of gluconic hydrazide, i.e., CH OH(CHOH) CONHNH About 162 grams of water and 24.8 grams of aqueous 37% formaldehyde were placed in a beaker, mixed and the pH of the solution was adjusted to 8 with dilute sodium hydroxide. To the solution there was slowly added 10.8 grams of gluconic hydrazide while the pH of the solution was maintained at about 8 by incremental addition of dilute sodium hydroxide. About 2.6 grams of MgCl .6H O was added to the solution and it was padded to the extent of 87% by weight wet pick-up on 78/84 white cotton sheeting having an original crease angle of 74. The cloth was dried and then cured at 360 F. for 4 minutes. After the curing step the cloths were scoured at 60 C. in an aqueous perborate solution containing a wetting agent. They were rinsed free of suds, dipped into a 1 percent by weight acetic acid solution for 15 seconds at about 50 C. and finally rinsed in water. After being pressed with an iron until almost dry, the test pieces of cloth were placed in a constant humidity (60 percent RH.) and temperature (72 F.) room for 24 hours in order to standardize the cloth for testing. The cloth then demonstrated a crease angle of 133 and contained about 9% added weight due to the treatment with the polymethylol hydrazide.

What is claimed is:

1. A method for the impregnation of a textile fabricated from a material selected from the group consisting of cellulose and regenerated cellulose to render it resistant to creasing and wrinkling which includes the steps of impregnating the textile with a solution of a reaction product of formaldehyde and a hydrazide of the formula RCONHNHR obtained by reacting formaldehyde and the hydrazide in a molar ratio of formaldehyde to the hydrazide within the range from 2 to 20, said reaction product being soluble in water to the extent of at least about 5 percent, and heating the impregnated textile to dry it and provide a textile resistant to creasing and wrinkling; R in thehydrazide being selected from the group consisting of hydrogen, alkyl of 1 to 8 carbon atoms, and alkyl of 1 to 8.carbon atoms substituted with at least one of the groups hydroxyl and sulfhydryl, R in the hydrazide being selected from the group consisting of hydrogen and 2. The method of claim 1 wherein the reaction between the formaldehyde and hydrazide is carried out at a pH of from 7 to 10.

3. The method of claim 1 wherein the hydrazide is acetic hydrazide.

4. The method of claim 1 wherein the hydrazide is glycolic hydrazide.

5. The method of claim 1 wherein the hydrazide is diformic hydrazide.

6. The method of claim 1 wherein said solution utilized in the step of impregnating the textile contains from 0.1 to 2 percent by weight of an acid-acting curing catalyst.

7. The method of claim 1 wherein said textile is cotton.

8. The method of claim 7 wherein said catalyst is magnesium chloride.

9. The method of claim 7 wherein said catalyst is ammonium p-toluene sulfonate.

10. A textile fabricated from a material selected from the group consisting of cellulose and regenerated cellulose which has been rendered resistant to creasing and wrinkling by the process of claim 1.

11. A cotton textile which has been rendered resistant to creasing and wrinkling by the process of claim 1.

12. A cotton textile which has been rendered resistant to creasing and wrinkling by the process of claim 2.

13. A cotton textile which has been rendered resistant to creasing and wrinkling by the process of claim 3.

14. A cotton textile which has been rendered resistant to creasing and wrinkling by the process of claim 4.

RCONHNI-LR obtained by reacting formaldehyde and the hydrazide in a molar ratio of formaldehyde to the hydrazide within the range from 2 to 20; R in the hydrazide being selected from the group consisting of hydrogen, alkyl of l to 8 carbon atoms, and alkyl of 1 to 8 carbon atoms substituted by at least one of the groups hydroxyl and sulfhydryl, R in the hydrazide being selected from the group consisting of hydrogen and 17. The composition of claim 16 wherein the hydrazide is acetic hydrazide.

18. The composition of claim 16 wherein the hydrazide is glycolic hydrazide.

19. The composition of claim 16 wherein the hydrazide is diformic hydrazide.

References Cited in the file of this patent UNITED STATES PATENTS Finlayson et al. June 13, 1939 Rudner July 29, 1958 

1. A METHOD FOR THE IMPREGNATION OF A TEXTILE FABRICATED FROM A MATERIAL SELECTED FROM THE GROUP CONSISTING OF CELLULOSE AND REGENERATED CELLULOSE TO RENDER IT RESISTANT TO CREASING AND WRINKLING WHICH INCLUDES THE STEPS OF IMPREGNATING THE TEXTILE WITH A SOLUTION OF A REACTION PRODUCT OF FORMALDEHYDE AND AHYDRAZIDE OF THE FORULA RCONHNHR1 OBTAINED BY REACTING FORMALDEHYDE AND THE HYDRAZIDE IN A MOLAR RATION OF FORMALDEHYDE TO THE HYDRAZIDE WITHIN THE RANGE FROM 2 TO 20, SAID REACTION PRODUCT BEING SOLUBLE IN WATER TO THE EXTENT OF AT LEAST ABOUT 5 PERCENT, AND HEATING THE IMPREGNATED TEXTILE TO DRY IT AND PROVIDE A TEXTILE RESISTANT TO CREASING AND WRINKLING; R IN THE HYDRZIDE BEING SELECTED FROM THE GROUP CONSISTING OF HYDROGEN, ALKYL OF 1 TO 8 CARBON ATOMS, AND ALKYL OF 1 TO 6 CARBON ATOMS SUBSTITUTED WITH AT LEAST ONE OF THE GROUPS HYDROXYL AND SULFHYDRYL, R1 IN THE HYDRAZIDE BEING SELECTED FROM THE GROUP CONSISTING OF HYDROGEN AND 